A wiper system according to the invention comprises the driven wiper arm as well as the wiper blade to be fastened on its one exposed end. The connection device required for this has appropriately developed coupling means corresponding with each other on the arm side and the blade side.
In the case of a known wiper system (DE 23 13689 A1), the wiper blade belonging to the wiper system and its coupling pan has a guide channel open toward a main body of the wiper strip, in which a hair pin-shaped retaining spring is displaceable between an installation position and a locked position. This retaining spring serves to open or close a recess located in the coupling part that represents the bearing receptacle for the wiper arm-pivot bolt. The retaining spring is preloaded toward a rubber main body of the wiper strip so that the friction between the rubber and the spring must be overcome in order to displace the spring. On the one hand, the ability of the spring to be displaced must be easy to manage for the user, e.g., when replacing the wiper blade, and, on the other hand, the spring must reliably close the bearing receptacle in the channel wall during the wiping operation so that the wiper blade cannot detach unintentionally from the wiper arm. These two opposing requirements cannot be fulfilled equally to satisfaction.
In the case of another wiper system (DE-PS 10 28 896) that does not have this deficiency, a coupling part on the wiper blade side is integrally molded to the rubber-elastic wiper strip. The coupling part has a bore-type bearing receptacle for a pivot bolt on the arm side that can be inserted in the bearing receptacle of the wiper blade transversely to its longitudinal axis via an elastically-expandable installation slot. This type of articulation may function reliably at best at low driving speeds and in the presence of small amounts of precipitation in the form of rain. When precipitation is strong and/or driving speeds are high, or precipitation is present in the form of snow, particularly in the form of wet snow, the forces exerted by the wiper blade on the articulation can exceed the holding power of the rubber-elastic coupling part and detach the wiper blade from the wiper arm.
The wiper system according to the invention is unique by virtue of a simple end functionally-secure articulation between the wiper arm and wiper blade. The attach the wiper blade to the wiper arm, its pivot bolt is inserted into the bearing receptacle of the wiper blade while the bottleneck is temporarily elastically expanded, whereby the locking element is moved into its open position against the return force, so that the pivot bolt reaches it bearing receptacle. The return force then automatically moves the locking element into Its locked position. The locking element can be produced out of a material that is so stiff that the operating forces acting on the point of articulation are absorbed between the wiper blade and the wiper arm without any negative consequences for the articulation.
A simple design of the wiper system results from the fact that the coupling part has a housing part that is permanently interconnected with the wiper blade, on which said housing part the locking element is displaceably guided in the longitudinal direction of the wiper blade.
In order to obtain a particularly robust design of the coupling for attaching the wiper blade to the wiper arm, the housing part has two guide walls that extend in the longitudinal direction of the wiper blade and are located at a distance from each other, between which the locking element is displaceably guided.
When, in a further embodiment of the invention, the bearing receptacle for the pivot bolt of the wiper arm penetrates the two guide walls as well as the locking element, whereby the recesses in the guide walls adapted to the cross section of the pivot bolt and the locking element located in the locked position complement each other to at least approximately form a circle, as viewed in the direction of the axis of articulation, the result is a functionally-secure, free-from-play fixing into position of the wiper arm-side pivot bolt in the coupling part of the wiper blade, therefore resulting as well in a smooth motion of the wiper blade over the window to be wiped. So that the wiper blade can also be attached to the wiper arm by individuals not skilled in the art, each of the bearing receptacle sections developed in this fashion is open toward the side of the coupling part opposite from the window over one section of the pass-through channel each, whereby the width of each pass-through channel section is greater than the diameter of the pivot bolt.
The locking element is preferably loaded toward the locked position by spring means supported on the housing part. This can be obtained in cost-effective fashion by means of a helical compression spring forming the spring means.
Installation of the coupling part can be simplified by the fact that the spring means are formed by a leg spring interconnected as a single component with the housing part composed of an elastic plastic.
When the bearing section of the locking element is provided with a starting incline that is opposite from its recess at a distance and that forms an acute angle xcex1 with the direction of displacement of the locking element, the detachment of the wiper blade from the wiper arm can be achieved in simple fashion by moving the locking element into its open position, whereby the starting incline presses the pivot bolt out of the bearing sections into the guide walls.
A permanently stable guidance of the locking element between the two guide walls is obtained when the two guide walls are interconnected by a bridge at one end section of the housing part.
In order to prevent mistakes during installation of the locking element in the housing part, the housing part has means for ensuring a defined working motion for the locking element located at a distance from the wiper strip.
These means can be formed in cost-effective fashion by means of at least one strip-like projection on the inside of one guide wall that extends in the direction of the working motion of the locking element and with which a longitudinal groove matched to the cross section of the projection and located on the side wall of the locking element facing the projection is associated.
To secure the locking element in the housing part, a limiting shoulder pointing in the direction opposite from the working direction is situated on said housing part, which said limiting shoulder cooperates with a counter-shoulder located on the locking element.
A further means for obtaining a free-from-play guidance of the wiper blade on the wiper arm can be obtained by the fact that the wiper arm has two side walls situated at a distance from each other and parallel to each other at least in the region of the pivot bolt, which said side walls are arranged standing upright on the window, and on which the ends of the wiper arm are fastened, whereby the distance between the two side walls is matched to the width of the coupling part. The two side walls therefore overlap the outer sides of the two guide walls opposite from each other in a manner that is free from play and covers a large area.
A particularly low and easy-to-build wiper blade is obtained when the coupling part is held on the top surfacexe2x80x94opposite from the windowxe2x80x94of a band-like long-straggling, spring-elastic carrier element, whereby it lies flat on said carrier element over at least one subsection, and when, furthermore, a rubber-elastic wiper strip capable of being placed against the window and arranged parallel to the longitudinal axis is located on the bottom band surface of the carrier element facing the window.
Further advantageous further developments and embodiments of the invention are presented in the subsequent description of exemplary embodiments illustrated in the associated drawings.